Avian Influenza - Causes, Symptoms and Treatment .MF .

August 12, 2017 17:52 | Infectious Diseases

Avian influenza - a viral infection of birds with high contagious, which can take place among them as asymptomatic or cause death.In recent years, one of the avian influenza strains became pathogenic to humans.Carriers of infection are mostly wild birds (waterfowl - geese, ducks), which practically do not get sick, but have a tendency to migrate from place to place and thus carry the virus over long distances.Pet bird species susceptible to infection with avian influenza virus, it is chickens, turkeys.

avian influenza was first reported in 1997, when an outbreak of the disease among men was registered in Hong Kong with lethal to 60%.Next, the H5N1 virus has spread from Asia to Europe and Africa.In Russia, the avian influenza A (H5N1) in poultry in the previous years was registered in Novosibirsk, Kurgan, Chelyabinsk, Tambov, Tula regions and the Altai.A few years ago from the dangerous disease has killed more than 200 swans in the Astrakhan region.Previously periodically avian influenza circulating in

Western Europe.In 2003, outbreaks of avian influenza type A (H7N7) was registered in the Netherlands, during which 89 people fell ill, one with fatal consequences on pulmonary complications.

epidemiological situation in 2013: In April 2013, China's outbreak of avian influenza A (H7N9), in which sick of about 130 people (32 people died).According to WHO, in August-September 2013, cases of avian influenza have been reported in poultry at farms in Italy, have been identified highly pathogenic H7N7.Several hundreds of thousands of birds are exposed to slaughter because of the outbreak of avian influenza.This strain of the virus at a specific mutation may well be pathogenic to humans.Also at this time it was recorded case of avian influenza in a farm employee.In this regard, the chief state sanitary doctor of GGOnishchenko instructed epidemiologists inform the public about the situation of the epidemic and health professionals to be more attentive to patients with SARS, staying in Italy.In recent years, China emerged as the highly for human strain of influenza A virus (H7N9).

causes of avian influenza

avian influenza virus belongs to the family Ortomyxoviridae, to influenza viruses type A virus complex structure.Is an RNA virus, are known two proteins in the outer shell - hemagglutinin (function viral attachment to the target cell, the host, as well as to produce antibodies, including protective, i.e. development of immunity) and neuraminidase (function virus penetration into the target celland viral replication inside the cell).There are currently investigated several subtypes of hemagglutinin and neuraminidase, thus distinguish different antigenic types of avian flu virus.Antigenic type H7N7 is able to cause the so-called "chicken plague", and H5N1 - the death-universal chicken.These two types of highly poultry (birds 100% mortality within 48 hours).There are also low pathogenic strains (bird, or are carriers of infection, or transfer it in an easy manner).

avian influenza virus

highly pathogenic avian influenza virus to humans?Previous 10-12 years showed that the H5N1 and H7N7 viruses mutate rapidly, which significantly affect their properties.Now they can easily go beyond bird populations passing through the pig body and distributed to people who are increasingly being diagnosed severe infections, as well as for lightning fatalities.

source of infection - wild waterfowl (ducks, geese) and poultry (chickens, turkeys).The virus is found in the intestines and is excreted in the faeces.

poultry deaths from bird flu

mechanism of infection - aerogenic (path - airborne).Most cases of avian influenza in humans is associated with an actual contact with sick poultry (live or dead).Transmission of the virus from person was not registered to the person.

Symptoms of bird flu in humans

duration of the incubation period (from infection to onset of symptoms) for influenza A (H5N1) usually 2-3 days, but can range from 1 to 8 days, and in rare cases up to 2 weeks.

Symptoms can be grouped in several clinical syndromes:
1) infectious-toxic;2) respiratory;3) gastrointestinal.

Home avian influenza always acute, due to its high pathogenicity for humans.It appears stunning chills, runny nose, sore throat, muscle aches.Often patients are concerned violation of a chair up to the watery, often repeated vomiting.The most constant symptom - an increase in body temperature to 38-40º, being the first day of illness immediately high.After 2-3 days, there is respiratory syndrome: often develop primary viral pneumonia (in patients pronounced cough with clear sputum, sometimes with blood, quickly joins dyspnea).When listening - hard breathing and crackles.

During the X-ray of the chest early in the disease exhibit multiple, sometimes extensive inflammatory infiltrates, which feature in the rapid merger and spread beyond the primary tumor inflammation;sometimes equity seals.

further development of the disease leads to the development of complications: respiratory failure and acute respiratory distress syndrome (ARDS).ARDS accompanied by a pronounced inflammation of the lung tissue total, gross violations of breathing, oxygen deficiency and the development of pulmonary edema.Often, the development of this complication is fatal for the patient.

Respiratory distress syndrome

in the peripheral blood of patients defined: reduction of white blood cells (& lt; 2,10 • 109 / L), a decrease of lymphocytes, and platelets.

Manifestations of avian influenza may be a violation of liver and kidney function, more than one third of patients develop acute renal failure.In the blood increases the level of ALT, AST, and creatinine.

Young children (under 3 years) get sick very seriously.Often the virus overcomes the blood-brain barrier and develops encephalitis (inflammation of the brain tissue).To add the existing complaints expressed headache with vomiting, disturbance of consciousness possible.

Risk factors for severe: delays in seeking medical care, initially low levels of white blood cells (immune deficiency), the presence of comorbidities.

forecast is usually unfavorable. Mortality reaches 50-60%.The lethal outcome is usually observed on the second week of illness.

Immunity after undergoing type-specific infection, intermittent.Perhaps re-infection in another season.

diagnosis of avian influenza

Due to the similarity of symptoms of avian influenza A (H5N1) to the symptoms of regular flu put a correct diagnosis at the beginning of the disease is difficult.Assist reports of outbreaks of influenza A (H5N1) in poultry or death of patients in places of residence;contact with a patient, which confirmed infection with influenza A (H5N1), as well as unknown SARS in the last 7 days before the onset of clinical signs;coming from a country where recorded outbreak of avian influenza in poultry;as well as professional infection - veterinarians, poultry workers.

symptoms for suspected bird flu:

1. High fever, cough and shortness of breath in the first days of illness;
2. Breakdown of the chair (in the absence of mucus and blood in the faeces);
3. The rapid increase in the severity of symptoms.
final confirmation of avian influenza A (H5N1) may occur following methods:
- immunological methods (immunofluorescence test for H5 - antigen using H5 monoclonal antibodies or determination of specific H5 antibodies in paired patient sera),
- molecular genetic (PCRon the A / H5) methods,
- virological methods - virus isolation (viral culture positive to A / H5).

avian influenza Treatment

1) security measures: all patients with suspected bird flu admitted to hospital.The extract is carried out only after normalization temperature for 7 days.
2) Specific treatment includes antiviral drugs broad spectrum:
oseltamivir, or Tamiflu, Relenza or zanamivir, Arbidol, Alguire.
3) symptomatic treatment: fever is used in high-temperature reaction (paracetamol, Nise, ibuprofen).They have a reinforcing effect of antiviral therapy.

drugs that are not used in the treatment of influenza A (H5N1): salicylates (aspirin), analgin.Analgin and Antigrippin absolutely contraindicated for the treatment of avian flu.

Antibiotics are appointed only in cases of suspected pneumonia mixed nature (ie, viral and bacterial).In severe pneumonia with the threat of complications appointed hormones.

Preventive treatment or prevention of an emergency. As a means of prevention is recommended emergency drug Amiksin, TSikloferon and other inducers of interferon.Efficacy of interferon inducers the higher than previously performed their function.They recommended risk groups and medical personnel in infectious hospitals in the care and treatment of patients with influenza pneumonia.

prevention of avian influenza

WHO recommends vaccinations conventional influenza vaccine in endemic areas of bird flu.This is to ensure that there is no contact with the two pathogenic strains of influenza A virus to one person, which, of course, will cause lightning during the avian flu.

risk groups for vaccination include:

1. Contacts with poultry or poultry farms suspected of being infected with avian influenza (H5N1).
2. Health professionals working with patients with H5N1 flu.

specific vaccine against avian influenza for a wide application has been received among the population.
Chemoprevention of avian influenza carried out by designated interferon inducers (tsikloferona and amiksina) algirema, rimantadine, Arbidol and oseltamivir (Tamiflu) as antiviral drugs.Prevention subject to all contacts in the outbreak of avian influenza, as well as farm workers.
Currently, the main concern is the possibility of transmission of the virus from person to person.This will lead to the development of severe and extensive bird flu pandemic, gripping the scale, many countries and continents.

infectious disease doctor Bykov NI